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POSimple SQL Server COUNT query (counting changes to values in a column)
 

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  1. POSimple SQL Server COUNT query (counting changes to values in a column)
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    <p>I have a table with columns: <code>MONTH</code>, <code>YEAR</code>, <code>PROJECT_ID</code>, <code>STATUS</code>.</p> <p>Status can be:</p> <ul> <li><strong>R</strong> (red).</li> <li><strong>A</strong> (amber).</li> <li><strong>G</strong> (green).</li> <li><strong>N</strong> (not started).</li> <li><strong>C</strong> (completed).</li> </ul> <p>I want to know how many projects completed in a given month i.e. :</p> <pre><code>where STATUS changed from anything that is NOT C to C; </code></pre> <p>It sounds simple...!</p> <p>It's easy to find when any given project completed with:</p> <pre><code>SELECT TOP 1 MONTH,YEAR,PROJECT_ID FROM Table WHERE PROJECT_ID=9236 AND RAG='C' ORDER BY YEAR ASC, MONTH ASC </code></pre> <p>But given <code>year = 2011</code> and <code>month = 8</code> (for example), I have no idea how to find the number of projects that had <code>status='C'</code> for the first time that month. Any ideas?</p> <p><strong>Edit:</strong> projects are still included as rows with <code>status='C'</code> after they complete, so I can't just count the Cs as that will return the number of projects that completed in this AND previous months (hence the chronological ordering and select top 1).</p> <p><strong>Sample data for 10/2010 to 01/2011 months:</strong></p> <pre><code>Month | Year | Project | Status ------------------------------- 10 | 2010 | A | G 11 | 2010 | A | C 12 | 2010 | A | C 1 | 2011 | A | C 10 | 2010 | B | R 11 | 2010 | B | R 12 | 2010 | B | R 1 | 2011 | B | R 10 | 2010 | C | G 11 | 2010 | C | G 12 | 2010 | C | G 1 | 2011 | C | C 10 | 2010 | D | A 11 | 2010 | D | C 12 | 2010 | D | C 1 | 2011 | D | C </code></pre> <p>^ Projects A and D was completed in 11/2010. Project B hasn't changed to completed in any of the four months shown. Project C was completed in 01/2011. {Month,Year,Project} is the primary key.</p> <p>So, inputs and outputs would be:</p> <pre><code>10/2010 =&gt; 0 11/2010 =&gt; 2 (because of A and D) 12/2010 =&gt; 0 1/2011 =&gt; 1 (because of C) </code></pre>
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    1. USChris
    1. USChris
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    1. COWhat do you mean by **for the first time that month**??, and why didn't you just query for: `select count(*) from tablename where year = 2011 and month = 8 and status = 'C'`
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      1. USMahmoud Gamal
    2. COShould read: ...that had status='C' for the first time, i.e. the project finished, that month. Your query would give me the number of completed projects, but not the number of projects that had completed THAT month. Projects are included in future months even after completing, with status still equal to 'C'. Sorry, there's a lot I could have been clearer about!
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      1. USChris
    3. COCould you provide some data sample (don't have to be real data) and expected result? It will make your question more clear
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      1. USBartekR
 

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